Evaluation of Prognostic Factors for Unresectable or Recurrent Gastric Cancer Treated with Nivolumab

Purpose Nivolumab is useful for the treatment of unresectable/recurrent gastric cancer as third-line or later chemotherapy. However, the factors that predict the efficacy of nivolumab monotherapy remain unclear. Methods We retrospectively studied the predictive factors of response in 59 consecutive patients treated with nivolumab as third-line or later chemotherapy for unresectable/recurrent gastric cancer at our hospital from October 2017 to May 2020. Results The median follow-up was 5.9 months. The study included 45 men and 14 women (median age: 71 years). We observed that 7 patients had an Eastern Cooperative Oncology Group performance status of 0 and 52 patients had a performance status of 1-2. Forty-three patients were treated with third-line therapy, seven with fourth-line therapy, and three with fifth-line therapy. The response rate to nivolumab was 6.7% and disease control rate was 35.5%. There were 19 (32.2%) immune-related adverse events for all grades and 9 (15.2%) for grades 3 and 4. Progression-free survival was 1.90 months, and overall survival was 6.30 months. Patients with immune-related adverse events had significantly longer overall survival than those without immune-related adverse events. Multivariate analysis showed that the occurrence of immune-related adverse events and a ratio for neutrophil-to-lymphocyte ratio after 8 weeks of nivolumab treatment to the baseline neutrophil-to-lymphocyte ratio before treatment of <= 1.5 were independent prognostic factors for overall survival. Conclusions Occurrence of immune-related adverse events and changes in neutrophil-to-lymphocyte ratio during nivolumab treatment may help predict the therapeutic efficacy of nivolumab monotherapy for unresectable or recurrent gastric cancer.